media: dib0700: fix rc endpoint lookup

Make sure to use the current alternate setting when verifying the
interface descriptors to avoid submitting an URB to an invalid endpoint.

Failing to do so could cause the driver to misbehave or trigger a WARN()
in usb_submit_urb() that kernels with panic_on_warn set would choke on.

Fixes: c4018fa2 ("[media] dib0700: fix RC support on Hauppauge Nova-TD")
Cc: stable <stable@vger.kernel.org>     # 3.16
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/usb/dvb-usb/dib0700_core.c

@@ -818,7 +818,7 @@ int dib0700_rc_setup(struct dvb_usb_device *d, struct usb_interface *intf)
 
 	/* Starting in firmware 1.20, the RC info is provided on a bulk pipe */
 
-	if (intf->altsetting[0].desc.bNumEndpoints < rc_ep + 1)
+	if (intf->cur_altsetting->desc.bNumEndpoints < rc_ep + 1)
 		return -ENODEV;
 
 	purb = usb_alloc_urb(0, GFP_KERNEL);
@@ -838,7 +838,7 @@ int dib0700_rc_setup(struct dvb_usb_device *d, struct usb_interface *intf)
 	 * Some devices like the Hauppauge NovaTD model 52009 use an interrupt
 	 * endpoint, while others use a bulk one.
 	 */
-	e = &intf->altsetting[0].endpoint[rc_ep].desc;
+	e = &intf->cur_altsetting->endpoint[rc_ep].desc;
 	if (usb_endpoint_dir_in(e)) {
 		if (usb_endpoint_xfer_bulk(e)) {
 			pipe = usb_rcvbulkpipe(d->udev, rc_ep);